Field of the Invention
The present invention relates to a magnetic field sensor and, in particular, to a magnetic field sensor provided with an indicator which indicates the presence or absence of a magnetic field.
Description of the Related Art
It is known to provide a magnetic field sensor with a light-emitting diode indicator. U.S. Pat. No. 4,296,410, which issued on Oct. 20, 1981 to Higgs et al., discloses an integrated circuit including a Hall element and a threshold detector. The threshold detector is encased in a plastic housing with the plane of the Hall element parallel with a face of the housing to provide a two-state Hall element proximity sensor. A light-emitting diode is mounted in the housing and is connected to the output of the detector. This provides visual indication of the state of the sensor. A kit includes the sensor and a compatible magnet which may be used as a proximity sensor in a security alarm system.